A piston is known from WO 2007/036357 A1, which is incorporated by reference. In this case, the piston is provided in a disk brake in such a way as to be movable electromechanically and hydraulically. In the case of electromechanical actuation, a drive spindle is set in rotation by an electric motor via a transmission. The drive spindle is in engagement with a drive nut, which is arranged in a manner secured against twisting in the piston. This enables the piston/drive nut unit to be moved axially in the cylinder. The drive nut can be placed axially against a conical surface in the piston and in this way transmits the axial movement to the piston and the brake pad.
In the case of parking brake calipers with “combined actuation” in parking brake systems, conventional brake caliper embodiments containing a mechanical actuating device with an integrated telescoping device for successive compensation of brake pad wear are taken to be fundamentally distinct. In this case, each replacement of worn brake pads requires manual resetting by the performance of a mechanical rotary return movement at the piston, thus turning a threaded means of the readjustment device back into an initial position. As a result, the brake piston is thereby moved into a rear end position, and the new brake pads can be installed.
In addition, there are caliper embodiments with an electromechanical actuator integrated into the caliper (electric parking brake) containing an electronic pad wear compensation system, and wherein an electronic mode is provided for moving the actuator electromechanically into a predetermined position for changing the brake pad. This eliminates the need for manual resetting. However, the decades-old manual resetting facility should be retained, at least as a fallback solution. There can be problems in the case of these brake calipers with situations in which there is an attempt at a continued manual resetting movement, even after the rear end position has been reached. This is because an unnecessary continuation of the operation merely promotes unwanted wear without having any positive effects. In this embodiment therefore—as in the case of all maintenance work on a brake system—special care and caution is required.